This invention relates to ultramicrotome knives and in particular, to anti-curl devices for ultramicrotome knives produced by fragmenting a glass-like substance and holders therefor.
Ultramicrotomes are used to produce specimen slices which are extremely thin in comparison with the usual microtomes. For example, a conventional microtome will produce specimen slices having thicknesses in the order of one micron. Ultramicrotomes, however, are used to produce slices as thin as 50A. These slices are so thin that it is frequently impossible to see the same without optical assistance and are so fragile as to cause extreme difficulty in removal and handling.
Because of the fragility of the ultra-thin slices produced by ultramicrotomes, the specimen slices have conventionally been collected by floating the same on fluids. Usually, the ultramicrotome knife is surrounded or partly surrounded by a small trough in which a fluid having a density greater than the specimen is contained. As specimens are cut, they float on the liquid and may be collected therefrom. This procedure has two disadvantages. The first is that there is an ever- increasing demand for cryogenic temperatures during sectioning. While fluids, such as dimethyl sulfoxide, may be used to temperatures of about -50.degree. C., at lower temperatures, fluids are not available for floating section slices. It has also been recently determined that some form of ion exchange action takes place between the tissue section and the support fluid. This ion exchange action has deleterious effects on the tissue specimen and complicates both examination and analysis.
Steel microtome knives, which are used to cut specimen thicknesses of one micron or more, have a regular back surface. The regularity of the back surface makes it relatively easy to provide an anti-curl device. Such devices are disclosed in U.S. Pat. Nos. 3,599,523; 3,699,830 and 3,733,948. If the knife is a conventional knife, rather than disposable, the anti-curl device is conventionally a flat plate piece of glass or plastic which is adjustable to be positioned in a parallel-spaced relationship to the knife back. In operation, the specimen section proceeds from the knife edge as it is cut to the space between the anti-curl device and the knife back.
It is an object of the present invention to provide an anti-curl device for irregular shaped microtome knife backs;
It is another object of the present invention to provide an anti-curl device for glass ultramicrotome knives; and
It is still another object of the present invention to provide a holder for ultramicrotome knives and anti-curl devices.